1. Field of the Invention
The present invention relates to the shaping and tempering of glass sheets of different configurations using a horizontal processing technique that avoids the need for tongs, which distort the glass locally during its processing.
Shaped, tempered glass sheets are used in automobiles both in the rear windows and in the side windows thereof. The side windows are relatively short and are conveniently shaped about axes extending essentially longitudinally of the initial path of movement through a furnace. Rear windows are elongated across the width of the installed vehicle and are bent about an axis that extends from the roof of the car toward the rear portion of the body. Prior to the present invention, apparatus for bending side lights was not necessarily used for shaping rear windows, and vice versa. However, with the automobile production rate decreasing, there is a need to provide equipment that operates more universally so that the equipment need not be idled for extended periods when order books are small.
The capital costs for fabricating apparatus for shaping and tempering glass sheets represents a relatively large investment in the construction and installation of a furnace and additional expenditure for the cooling station. When prior art constructions are used in the manner for which they were designed, a separate furnace is needed for apparatus to make rear windows and a separate furnace is needed to make side windows. Wide furnaces suitable to handle rear windows transported sidewise for passage in a straight line through the furnace to a shaping station for shaping about an axis along the initial path of travel and thence through a cooling station would be too wide to handle smaller side windows and would be inefficient if used to process the shorter side windows. Narrower furnaces suitable to process back windows by conveying them lengthwise through the furnace, shaping them to a desired shape and then transferring them laterally after shaping into a cooling station disposed to one side of the shaping station have been developed, and apparatus has been made in the past to shuttle bent glass sheets to opposite sides of an initial path alternately for cooling prior to returning the cooled sheet to a continuation of the initial path.
There have been prior apparatus combining more than one cooling station with a single furnace. However, we are not aware of any that could be readily employed either for the fabrication of shaped automobile backlights or shaped automobile sidelights without substantial dismantling and rebuilding of the apparatus. It would be desirable for the glass sheet and tempering art to develop apparatus that was capable of being so used with only minor adjustments needed to convert the apparatus from a capability to produce rear windows to one for producing side windows, and vice versa.
2. Description of Patents of Interest
U.S. Pat. No. 3,684,473 to Ritter discloses glass sheet bending and tempering apparatus comprising a common furnace and a pair of cooling stations disposed on opposite transverse sides of a shaping station beyond the exit of the common furnace. The apparatus of this patent diverts alternate shaped sheets to opposite lateral sides of the shaping station to permit one glass sheet to be cooled while the next sheet is being shaped in the shaping station. All the glass sheets handled in this apparatus are of identical shape.
U.S. Pat. No. 3,846,106 to Seymour and U.S. Pat. No. 4,197,108 to Frank et al disclose apparatus for shaping and tempering glass sheets in which the glass sheets are deposited on a ring-like member after they are shaped at a shaping station and conveyed into a curved space defined by opposed sets of nozzles relative to an axis of bending that is aligned with a path of travel that the glass sheets take along a conveyor that extends through a heating furnace and into a cooling station. The glass sheets are shaped about an axis substantially parallel to the path of movement.
European Patent Publication No. 3391 to McMaster et al discloses a glass sheet shaping and tempering apparatus in which a single furnace is provided with a cooling station in any one, two or three positions, either longitudinally beyond the shaping station or to either side of the shaping station. All three stations can receive heated and bent glass for tempering to increase the system output. This patent also recognizes that the cooling station aligned with the longitudinal direction of the furnace can also be used to temper sheet glass that is not bent. The nozzles from the blastheads in this latter patent are arranged in vertically spaced, flat planes to provide a flat space through which bent glass sheets are conveyed during their cooling that follows their shaping step. This patent does not recognize the benefit of an access area to facilitate changing the mold in the shaping station. Instead, this patent relies on the glass sheet sagging onto a ring-like shaping member after it is transferred thereto from a vacuum holder.